I have several learning disabilities including dyslexia and ADHD and was also a top student, so those aren't exactly determinative. Many of my top students are neurodivergent. I get a dozen letters every semester from my top students regarding their learning disabilities.
Excelling in sports and music is also indicative of highly talented students with vast aptitude. Your kids are actually probably far above average, but you can't see that, because your N=2.